Electron discharge device anode structure



Nov. 15, 1955 H. w. LARSON 2,724,071

ELECTRON DISCHARGE DEVICE ANODE STRUCTURE Filed Oct. 1. 1951 INVENTOR H. W/ZL/AM LARSON United States Patent ELECTRON DISCHARGE DEVICE ANODE STRUCTURE Application October 1, 1951, Serial No. 249,068

2 Claims. (Cl. 313-3'56) This invention relates to electron discharge devices and more particularly to a new and improved anode structure for use in such tubes.

Many electron discharge tubes such as radio tubes and the like require the use of hollow metallic anode structures of rectangular, circular or irregular cross section, such members serving as the terminal point for electron flow within the electron structure of the vacuum tube. Many methods of fabricating these anode structures have been employed in the art and common forms of tube anode structures include the seamless copper tube frequently used as an integralportion of the envelope of a transmitting tube, the sheet metal tube having a lock seam, joint by which the ends of the sheet metal are sealed together, the use of two shaped members welded face, to face on supporting members, or most simply, one or two plane sheets of. metal appropriately located.

As thetube manufacturing art has progressed, the tendency has been towards the reduction in size of the vacuum tube and its associated electron structure in order to facilitate the manufacture of more compact equip 1 ment. As a result of this reduction in size of the electrode structure of the vacuum tube, greater difliculties have faced the fabricator of the vacuum tube who wishes to produce a simple and rugged vacuum tube at minimum cost. Anode structures, for example, have been so reduced in size that utilization of former anode structures has become impractical.

A principal object of this invention, therefore, is to provide a new and simplified vacuum tube anode structure.

Another object of this invention is to provide an anode structure particularly adapted for use in small tubes, especially those having bulbs of small tubular cross section.

A further object of the invention is to provide an anode structure adaptable to fabrication by automatic machinery.

A still further object of the invention is the simplification of anode structures by the elimination of unnecessary welds and complicated folded and overlapping joints.

Another object of the invention resides in the provision of a rectangular anode structure having superior mechanical strength.

A further object of the invention is the reduction in cost of anode structures for use in vacuum tubes through the use of a new, simplified and inexpensive structure.

Another object of the invention is reduction of time of manufacture of a simple, rugged anode structure which may be fabricated in a minimum number of steps comprising single cutting, bending and folding operations.

A still further object of the invention is to produce an uncomplicated anode structure of high rigidity in order to reduce variation in vacuum tube characteristics due to changes in electrode dimensions and relative electrode positions.

The above objects, and others which will appear to ice the reader, are attained in this invention by forming a tubular anode structure from a. piece of suitable sheet material, by joining together the ends of said sheet by means of projections disposed in alternation along either end of the sheet, and which, when the ends are brought together, interlock and fold onto the exterior surface of thesheet.

The invention will now be described. Reference should be made to the drawing in which:

Fig. 1 is a side view in partial cross section of a finished tube according to one embodiment of the invention; and Fig. 2 is a view in perspective of a portion of the anode structure shown in Fig. I.

, Referring now to Fig. 1, the numeral 2 designates a generally cylindrical glass envelope, the numeral 4 designates an anode structure of a vacuum. tube of a particular embodiment of the invention, and the numerals 6 designate mica spacers which are mounted at either end of anode structure 4 by means of tabs 8 which are extensions of anode structure 4 passing through mica 6 and overturned at a right angle to the anode structure, thereby retaining micas 6 in place. conventionally supported by the mica spacers within the hollow center portion of the anode 4 are filament or heater support 10 and grid side rods 12, on which. may be wound a wire (not shown) comprising the grid, and normally employed to control electron flow to anode 4. The grid may be omitted in a diode construction. and more than one grid supported by appropriate side rods similar to those shown may be used in a tetrode or other multi-grid form of vacuum tube. Numeral 3 indicates the tip-off point on the envelope 2 of the tube; i. e. the point at which the exhaust tubulation has been removed from the envelope in the final stages of processing of the tube. The wires 14 are lead-in connections from the outside to the inside of the tube and are hermetically sealed in the envelope 2 and connect with the variousinternal electrodes. The entire tube structure just described is of a generally conventional nature with the exception of the anode structure 4, and is illustrated and described merely as illustrative of a typical vacuum tube incorporating the anode of the invention.

In Fig. 2, as an aid in simplifying the drawing, the lower portion of the anode structureillustrated in Fig. 1 has been cut off, but it will be understood that the anode structure could be extended indefinitely and terminated at its lower end in a manner similar to that utilized at the top of the tube.

It will be seen that the anode of the presently described embodiment of my invention comprises a suitable punched or stamped sheet of metal folded over itself to form a hollow tube of rectangular cross section having two major walls 16 and 17, and two minor walls 19 and 20. At the top of major walls 16 and 17 are cutout portions 18, ordinarily included in anode structures to permit inspection of the assembly of grids and cathode within the anode. Attached to minor walls, 19 and 2t), and extending vertically upwards, therefrom are tabs 8. These are tabs which will be used at a later stage in the assembly of the tube to hold the micas in place. In,

the present embodiment of the invention the edges of the sheet metal, which are placed in juxtaposition to close the anode body and provide electrical continuity, are brought together at one corner of the rectangular anode structure.

Projections 22 and 24 are integral (but need not necessarily be so) with major wall 16 and minor wall 20, respectively, and are disposed in alternation in complemeo v relation along the opposite ends of the sheet, so that when the ends are brought together the complementary projections intermesh or interdigitate, thereby permitting the metal edges at the base of the projections to come together. Projections 22 and 24 are then folded over so that projections 22, for example, lie flat on the outside of minor wall 20 and so that, similarly, projections 24 are foldedover and lie against the outside of major wall 16.

This method of forming the joint serves to force the ends of the walls closely together, and to hold them there permanently and firmly. Inspection of the drawing will show that by pressing tab 24 against side wall 16, side wall 16 is thereby pressed firmly against the end of side wall 20 at the root of projections 22. Similarly, pressure by projections 22 against side wall 20 serves to cause the inner portion of side wall 20 to press against the end surface of major side 16. The resulting structure presents a tubular body of considerable rigidity, and is capable of fabrication without the use of welds, solder, or lock seams of a complex nature.

Construction of this anode may be relatively simple. Using suitable dies, a correctly formed sheet of metal for use in the anode can be stamped out. Then, using a mandrel fitted to the inner dimensions desired, the anode (e. g. the major and minor sides) may be formed by wrapping the sheet around the mandrel. The anode tube will then be completed by folding and pressing first one set of projections, such as those numbered 22, against the minor face of the anode sheet. Similarly, projections .24 will be forced and pressed against major face 16.

The resulting anode structure, when slid off the mandrel, will be ready for assembly into the complete electrode structure of the tube illustrated in Fig. 1. It should be noted that the most suitable form of the invention is that in which the width of the projections is closely controlled so that, when the ends are brought together and caused to intermesh, there is a tight fit.

' It should be apparent that this structure is adaptable to many forms of anodes for use in vacuurn't'ubes, that its use need not be restricted to small tubes, that it is equally applicable to many other forms of tubular metallic structures, and that its use need not be restricted to tubular structures having square corners-rather that it may be used wherever sheet metal comes together at an angle. The particular embodiment herein described is particularly suitable for use in miniature tubes where anode structures are small and little working space is available for complicated operations with tools. It should be apparent, however, that the form of the invention described isnot restricted to employment in small anode structures which are rectangular in nature, but that it can be applied equally well to any structure of a sheet material.

Although a particular embodiment of the invention has been shown and described, it is not intended that the appended claims should be limited to the embodiment described, but rather that they should apply to all modifications which do not depart from the spirit and scope of the invention.

What I claim is:

1. An electron discharge device having a hermetically sealed envelope containing electrode structure including a tubular electrode open at its ends, said tubular electrode being a single sheet of metal with end portions meeting at a corner portion whose cross section is approximately right angular, said corner portion extending longitudinally of the tubular electrode, each of said end portions being provided with at least one projection, with the projections on each end portion overlying the exterior face of the adjoining end portion.

2. An electron dischargedevice having a hermetically sealed envelope containing electrode structure including a tubular electrode open at its ends, said tubular electrode being of a single sheet of metal with end portions meeting at substantially right angles, and projections on one of the end portions interdigitated with projections on the other end portion and each of the projections engaging the outside faces of the adjoining end portions.

References Cited in the file of this patent UNITED STATES PATENTS 198,161 Simpson Dec. 11, 1877 207,606 Ketcham Sept. 3, 1878 1,189,204 Kuentzel June 27, 1916 1,672,482 Crowley June 5, 1928 2,493,555 Simpson Jan. 3, 1950 Dan... 

